I feel like the trick is really being missed here when it comes to resist all. Why not make it so that say if there's an attack that deals 6 fire, 5 bludgeoning, 3 spirit damage and you have resist all 10 (like if you're a champion with oath of the defender) that instead of the resist all only applying to the highest damage type (in this case the fire damage meaning 4 points of mitigation are completely wasted) have it so you sum the damage types together and subtract the resistance from the total (meaning 6+5+3 = 14 total damage, resist 10 brings it down to 4)
this means no points of mitigation are wasted but you don't completely wipe the damage out like the old system.